This invention relates to a molding apparatus and method for sealing semiconductor devices in a resin, and more particularly, it relates to a molding apparatus and method in which a cleaner is provided for cleaning the surfaces of the mold of the molding apparatus.
Semiconductor devices are frequently sealed in a resin in order to protect them from the environment. A molding machine for sealing a semiconductor device in a resin generally comprises an upper mold half and a lower mold half which are respectively secured to a fixed upper platen and a movable lower platen. By raising and lowering the lower platen using a press, the two mold halves can be brought into and out of contact with one another.
It is conventional for this type of molding machine to be equipped with a cleaning device having rotating brushes which are moved back and forth across the surfaces of the mold halves to clean off any molding burrs, dust, and other foreign matter adhering to the mold surfaces after molding is performed. The foreign matter which is removed by the brushes is then blown off the mold surfaces by compressed air.
This type of cleaning device is usually mounted on the lower platen of the molding machine, and some of the foreign matter which is removed from the surfaces of the mold halves falls into the space atop the lower platen between the cleaning device and the lower mold half. As access to this space is difficult, foreign matter tends to accumulate in this location, and when the lower platen is lowered after molding, it is easy for some of this foreign matter to end up inside the lower mold half. If the foreign matter is present in the mold when the semiconductor device is sealed with a resin, the foreign matter can produce molding defects and impair the operation of the semiconductor.